A/n range system simulator



2 SHEETS-SHEET 1 E. T. HEALD A/N RANGE SYSTEM SIMULATOR AAAAAA IVVVVVINVENTOR. fA/IL 7.' HZALD BY 2 Filed Jan. 4, 1951 Dec. 16, 195.2

Dec. 16, 1952 HEALD 2,621,425

A/N RANGE SYSTEM SIMULATOR Filed Jan. 4, 1951 2 SHEETS-SHEET 2 (7y 5INVENTOR.

BY 51/24 7: A t/4L0 Patented Dec. 16, 1952 UNITED STATE ,tZlAZS FFICEA/N RANGE SYSTEM SIMULATGR Earl T. Heald, Pasadena, Calif., assignor toCollins Radio Company, Cedar Rapids, Iowa, at corporation of Iowa 9Claims.

This invention relates in general to apparatus for simulating the A/Nrange system of aerial navigation for a pilot training device.

In the training of pilots for aircraft it has generally been realizedthat some of the training may be given in a trainer which simulatesflight conditions but which in reality is fixed to the ground. Varioustypes of these trainers are known and generally the student pilot isplaced under a hood so that he cannot see his surroundings, but seesonly instruments of the trainer. The noise of a real airplane issimulated, and as far as the student is concerned, he is actually in anairplane. Some of the training in the simulator is for the purpose offamiliarizing the student with the control of the airplane through theuse of ailerons, rudder and elevators. He is taught to control thethrottle, mixture, propeller, landing gear, flaps, and other nightcontrols. Thus, in some measure a student pilot may familiarize himselfwith the complicated instruments and control apparatus before beingplaced in a real aircraft. Another very important phase of the trainingof a pilot is to teach him to fiy under instrument conditions. Undersuch conditions the pilot is out of visual contact with the ground andmust thus rely on his radio aids and his dead reckoning for hisgeographic position. One of the first radio aids for aircraft navigationwas the A/N range wherein a pilot flying within radio reception distanceof a range station receives either an A or an N signal unless he is onone of the legs of the range station, where he receives a steadyon-course signal. The presentation to the pilot might be aural oralternatively might be placed on a meter which has a needle thatindicates yellow or black and has a center oncoursefposition.

It is an object of this invention, therefore, to provide a simulated A/Nsystem for a ground trainer.

A further object of this invention is to provide an A/N system for atrainer wherein the student may become familiar with the A/N system.

A feature of this invention is found in the provision for an A/N rangesimulator comprising, an oscillator which feeds an aural input to acam-keyed phase-reversing circuit and wherein adding means adds theoutput of the oscillator to the output of the phase-reversing circuit to2 obtain an output indicative of the trainers position.

Further objects, features, and advantages of this invention will becomeapparent from the following description and claims when read in view ofthe drawings, in which:

Figure 1 is a schematic diagramof the range simulator of this invention;

Figure 2 is a detailed top view of the range leg selector of thisinvention; and,

Figure 3 is a sectional view taken on lined-3 of Figure 2.

Figure 1 shows an oscillator Ill which produces an output which mightbe, for example, 1,020 cycles per second. An output of the oscillator issupplied to point A through a resistor R1. A second output of theoscillator is supplied to a phase-reversing circuit whose output is fedto point A through the resistor R2. The signals are added at point A andsince the signals are either in phase or out of phase, respectively, theoutput from point A will have two distinct amplitudes with one beingmuch larger than the other.

The phase-shifting circuit comprises, a cam II which is mounted forrotary motion. As shown in Figure 1, the motion is counterclockwise.Th-e cam is formed with two indentions or recesses l2 and It with theindention I2 being substantially smaller than the indention 13. Theindentions l2 and it cover half of the circum ference of the cam l Ithus leaving projections 14 and I6, which constitute the other half ofthe circumference. The projection i4 is of the same ize as the recessl2, and the projection l 6 is of the same size as the recess l 3.

A spring loaded contact I! engages the outer periphery of the cam H andis spring-biased to follow the irregularities in the surface. Thuscontact I? moves between an outerand inner position as the cam isrotated. A positive voltage E1, as, for example, plus 20 volts, 'iselectrically 'connected to the contact I! and as it moves inwardly andoutwardly it makes and breaks contact with a lead it. When the contact His engaged by the projections It and 15; the lead !8 is not'connected tothe plus 20 volts, andwhen contact I1 engages the bottom of recesses12am [3 the plus 20 volts is connected to lead l8. Lead [8 isconnect'e'd to the grid of a tube V1 through a resistor R3. The plate [9of tube V1 is connected to one end of a balanced transformer whichcomprises an inductance L1 connected in parallel with condensers C1 andC2. The cathode 2| of tube V1 is connected to ground through theresistor 34. The center of inductance of L1 and the midpoint betweencondensers C1 and C2 are connected to a high voltage source E3. The gridof V1 is connected to E2, which might be negative 20 volts. The tube V1is adjusted so that it conducts when the contact I? Supplies plus 20volts to the lead 18 but does not conduct when the contact ll does notengage the lead l8. Thus, the tube V1 is triggered on and off inresponse to the rotation of the cam l l. A second tube V2 has its gridconnected to lead [8 and has its cathode 22 connected to ground througha resistor R5. The plate 23* of tube V2 is connected to the center pointof L1 and the mid point between C1 and C2 and to EB. The tube V2conducts very heavily when the contact l1 engages the bottom of recessesIt and it and conducts at a lesser rate when the contact ll engages theprojections Id and Hi, respectively.

A third tube V2, has its cathode 24 connected to the cathode 22 of tubeV2, and its grid 2'6 15 connected to ground through the resistor Rs andreceives a signal from the oscillator through a condenser C3. The tubeV1 also has its grid connected to the output of oscillator iii through acondenser C 1. Tube V2 conducts when the contact i1 is engaged by theprojections Hi and I6 and is cut oif when the contact it engages thebottoms of recesses 12 and it. This is true because the tube V2 iscathode-biased and the resistor R causes the tube V3 to be biased to cutoil when tube V2 draws a large amount of current. When the tube V2 drawsa smaller amount of current the Voltage developed across resistor R5 isless, and therefore the tube V3 conducts. The plate 21 of tube V3 isconnected to the lower end of inductance L1.

The inductance L1 is coupled to an inductance L2 which has its mid-pointconnected to ground and it is to be observed that the voltage EAdeveloped across the inductance L2 reverses phase in response torotation of cam H. This is true because the outputs of tube V1 and V3are connected to opposite ends of the transformer comprising L1 and L2and as tubes V1 and V3 are triggered, respectively, the voltage EA willreverse phase by 180 degrees. It is to be observed that only thealternating current components appear across the inductance L2 and sincethe output of oscillator I0 is 1,020 cycles, the voltage EA will have afrequency of 1,020 cycles. The voltage EA is applied to a range legselector which is shown in detail in Figure 2.

The range leg selector, designated generally as 28, comprises a circularresistor 29 which may be wound about a ring 3|, for example. Theresistor 29 is endless and closes upon itself. Four slide contactsdesignated as 32, 33, 34, and 3t, respectively, are grounded and areengageable with the resistance 29. The contacts 32 through 36 determinethe location of the four legs of the simulated A-N range station. Forexample, if the range to be simulated has on-course legs at 45, 135, 225and 315 degrees, respectively, the contacts 32 through 36 are set so asto engage the resistor 29 at these points. resistance 29 is establishedarbitrarily and in the example illustrated would be mid-way between thecontacts 33 and 34. It is to be understood of course that the legs of anA/N course do not necessarily all fall 90 degrees apart, and there- Areference on the 4 fore, contacts 32 through 36 may be set to the fourlegs of the system no matter where they lie.

Within the ring 3! four pivotally supported slide contacts 37, 3B, 33and H are mounted. The outer ends of these contacts are engageable withthe resistance 23 and the alternate contacts 3? and 3B, and 38 and 4!,respectively, are electrically connected together. The voltage EA acrossthe inductance L2 is applied across these contacts by slip rings ofother suitable means. The lead 42 is connected to one side of inductanceL2 and is connected to the contacts ll and 38 respectively, and the leadas is connected to the other side of inductance L2 and is connected tothe contacts El and 39, respectively. The contacts 3'1, 38, 39 and 6]are set at the mid-points between contacts 32, 33, 3t and 38. Forexample, if the contact 33 is set to 315 degrees and the contact 34 isset to 45 degrees, then the contact 31 will be set to zero degrees so asto fall mid-way between the two grounded contacts. Likewise, contact 38in the above example will be set to degrees, contact 39 to degrees andcontact 4! to 270 degrees.

It is to be understood, of course, that the contacts 3i through 41 neednot necessarily be set 90 degrees apart, but their angular position isdetermined by the mid-points between the grounded contacts 32 through36.

A rotatable slide contact i t is engageable with resistance 29 and isconnected to the point A through the resistor R2. The phase andamplitude of the signal picked-oil by the movable contact 3d dependsupon its position about the resistor 23. For example, if it is directlyopposite any of the grounded contacts 32, 33, 35 and 35, it will pick upno signal because it wil1 be connected directly to ground. On eitherside of the grounded contacts a signal of 1,020 cycles will be picked upwith the phase of the signal reversed on opposite sides of the groundedcontact and the amplitude linearly increasing until a maximum will bereached when the contact 44 is directly in contact with the feed-inpoint oppo- 'site contacts 37, 38, 39 and 4|.

The movable contact 44 is mechanically linked by linkage 36 to abearing-to-station computer 4?. The bearing-to-station computer includesa resolver which may contain a rho-theta computer and integratingcircuits. The bearing-tostation computer may be of a variety of typesand is well known to those skilled in the art. For this reason it willnot be described in detail herein. For a more detailed description ofsuch a computer, reference may be made to the patent to Agins, No.2,467,646.

Since the bearing-to-station computer maintains the contact 44 alwayspointing toward the station, the signal picked up will be a function ofthe bearing to station.

The signal from the oscillator i0 which is fed to a point A throughresistor R1 is added to the signal picked up by the contact l andfurnished through the condenser C5 to the grid of an amplifying tube V4.The output of the amplifier V4 is presented to the student and gives anindication of his position relative to the radio station. Thepresentation may be made by an aural signal which is listened to by thestudent, or may be made on a zero center meter which reads zero when heis on course and right or left when he is off course. If the contact idis between contacts 32 and 33, or 34 and 35, the aural output will be anA signal with the amplitude dependent upon the distance from thegrounded contacts. If the contact 44 is between contacts 33 and 34 orcontacts 32 and 36, an N signal will be picked up and the aural outputwill be an N signal.

Examples of component values are:

R1 ohms 82,000 R-z do 82,000 R3 do 560,000 R4 do 1,800 R5 do 18,000 R6d0 560,000 E1 volts positive E2 "volts negative. 20 EB volts 200 Figure2 is a top detailed view of the range leg selector 28 and shows thecontacts 32 through 54. The sectional view of Figure 3 illustrates abase member 43 to which is attached a cylindrical sleeve 0. Contacts 32,33, 34 and 38 are slidably connected to the top of sleeve 49. The member&0 is grounded through the plate 43 and thus the contacts 32, 33, 3t and36, respectively, are grounded. Mounted within the sleeve 49 is the ring3!. It is insulated from the sleeve 09 and base 48 by insulatingstandoifs 5!. Contacts 3i and are pivotally connected to a shaft 52which passes axially through the ring 3! and the plate 68. The contacts37 and 30 may be rotated relative to the shaft 52 but make electricalcontact therewith. Insulating material 53 fits about the shaft 52 andinsulates it from contacts 38 and 0! which are connected to cylinders 50and 56, respectively. The cylinders 50 and 53 extend downwardly throughthe ring BI and out an opening 5? formed in the plate '53. Insulatingmaterial 53 covers cylinder 56 and the contact is mounted to a cylinder53 which fits over the insulation 58. The cylinder 59 extends throughthe plate ts and has mounted thereon a worm gear 85. The worm gear 6|meshes with a gear 02 which is connected to shaft 46. The shaft isconnected to the bearing-tostation computer 4?. The lead 02 from theinductance L2 is connected to a contact 63 which engages the cylinder50. The lead 0.3 from the other side of L2 is connected to a contact 00which engages the center shaft 52. Thus the electrical inputs arefurnished, respectively, to contacts 3'? and 30, and 33 and 0!. All thecylindrical members may be rotated relative to each other so that therange leg selector may be set to simulate the desired range.

It is seen that this invention provides means for simulating an A/Nrange and although it has been described with respect to a preferredembodiment thereof it is not to be so limited that changes andmodifications may be made therein which are within the full intendedscope of the invention as defined by the appended claims.

I claim:

1. An A/N radio range simulator for a pilot training device comprising,an oscillator producing an alternating signal, a phase reversing circuitreceiving an output from said oscillator and reversing its phase by 180degrees during predetermined time intervals, a range leg selector havingan annularly wound resistor with four points of said resistor groundedto correspond with the geographic locations of the radio range stationbeing simulated, a first movable contact within said range leg selectorin contact with said annular resistor at the mid-point between the firstand second grounded points,a second movable contact with said annularresistor at the mid-point between said second and third grounded points,a third movable contact in contact with said annular resistor at themid-point between said third and fourth grounded points, a fourthmovable contact connected to said annular resistor at the mid-pointbetween the fourth and first grounded points, said first and thirdcontacts connected to one side of the output of said phase reversingcircuit, said second and fourth contacts engageable with the other sideof the output of said phase reversing circuit, a fifth movable contactengageable with said annular resistor, a bearing-to-station computermechanically connected to said fifth contact to move it in response tothe computed bearing to station, and the output of said fifth contact.added to an output of said oscillator to produce a signal indicative ofthe pilot trainers orientation with respect to the A/N range.

2. In apparatus according to claim 1, a phase reversing circuitcomprising, a balanced transformer, a first electronic valve with itsplate connected to one end of the primary of said balanced transformer,a second electronic valve with its plate connected to the centerpoint ofthe primary of said balanced transformer, and a third electronic valvewith its plate connected to the opposite end of the primary of saidbalanced transformer, an output of said oscillator connected to thegrids of said first, second and third electronic valves, a cam mountedfor rotary motion and formed with two projections with one of saidprojections being substantially larger than the other and saidprojections covering one half the circumference of said cam, a pawlengageable with the periphery of said cam to follow the irregularitiesin its surface, a switch actuated in response to movement of said pawlto connect abiasing voltage to the grids of said first and secondelectronic valves when the pawl is between projections on said cam, saidfirst electronic valve conducting only when said biasing voltage isconnected to its grid, said third electronic valve conducting only whenthe first electronic valve is not conducting, and an output voltageremoved from the secondary of said balanced transformer which reversesin phase by degrees as said biasing voltage is connected anddisconnected, respectively, to said grids.

3. In a synthetic A/N range system a phase reversing circuit receivingan output from an oscillator and comprising, a transformer, a firstelectronic valve with its plate connected to one end of the primary ofsaid transformer, a second electronic valve with its plate connected tothe mid-point of the primary of said transformer, and a third electronicvalve with its plate connected to the opposite end of the primary ofsaid transformer, an output from said oscillator furnished to the gridsof said first, second, and third electronic valves, a cam supported forrotary motion and formed with two projections with one of theprojections substantially larger than the other and said projectionscomprising one-half the periphery of said cam, a cam follower engageablewith the periphery of said cam and following the irregularities in itsperiphery, said cam follower connecting a positive biasing voltage tothe grids of said first and second electronic valves when engaged withthe low points of said cam, said first electronic valve conducting whenits grid is connected to said biasing voltage and not conducting whenits grid is not'connected to said biasing voltage, the cathode of sen tesaid third electronic valve connected to the oathode of said secondelectronic valve and biased to cut off when said biasing voltage isfurnished to the grids of said first and second electronic valves andconducting when said biasing voltage is not connected to said first andsecond grid, and the output voltage across the secondary of saidtransformer reversing in phase by 180 degrees in response to rotation ofthe cam.

4. In a synthetic A/N range device for a pilot training apparatus, aphase reversing circuit comprising, a transformer with one end of itsprimary connected to the plate of a first electronic valve, themid-point of its primary connected to the plate of a second electronicvalve, and the opposite end of its primary connected to the plate of athird electronic valve, a cam supported for rotary motion and formedwith two projections which cover one-half the periphery of the cam andwith one of said projections being substantially larger than the otherone, a cam follower engageable with the periphery of said cam, a biasingvoltage connected and disconnected respectively to the grids of saidfirst and second electronic valve in response to motion of the camfollower, said first electronic valve biased to cut-01f when said camfollower engages said projections, and biased to conduction when saidcam follower engages the recesses between projections, said thirdelectronic valve biased to cut-off when said cam follower engages therecesses between projections, and said third electronic valve biased toconduction when the cam follower engages said projections, and theoutput of the secondary of said transformer reverses in phase by 180degrees in response to rotation of said cam.

5. In an A/N range simulator for a pilot training device, a range legselector comprising, an annular member, a resistor wound transverselyabout said annular member and its ends connected together so as to forman endless resistor, a first set of four slidable contacts engageablewith said resistor and set to correspond with the legs of the A/N rangebeing simulated, a second set of four slidable contacts engageable withsaid resistor and set to the mid points between the first set ofcontacts, and alternate contacts of said second set of contactsconnected electrically together, a take-off contact supported for rotarymotion, engageable with said resistor and insulated from said first andsecond set of contacts and removing an output from said resistor whosephase and amplitude is dependent upon its annular position relative tothe resistor.

6. In an A/N range for a pilot training device Gil having an oscillator,a phase reversing circuit, a

range leg selector comprising an annular resistor, four groundedcontacts engageable with said resistor and set to correspond,respectively, to the legs of the A/N range being simulated, fourslidable contacts engageable with said resistor and set, respectively,to the mid-points between said grounded contacts and alternate slidablccontacts connected together electrically, said slidable contacts'eceiving the output of said phase reversing circuit, a take-off contactengageable with said resistor and removing an output there fromindicative of the pilot trainers orientation with respect to thesimulated station, and a bearing-to-station computer mechanicallyconnected to said take-off contact and moving it to always point towardthe simulated station.

7. In a simulated A/N range system for a pilot training device having anoscillator and a phase reversing circuit receiving an output from saidoscillator, a range leg selector comprising, a first hollow cylindricalmember, a resistor wound longitudinally about said first cylindrical memher with the ends connected together so as to form an endless resistor,a second cylindrical member supported about said first cylindricalmember, a plurality of slide contacts slidably connected to the upperend of said cylindrical member and engageable with said resistor, afirst pair of wiper blades engageable with said resistor, a shaftrotatably connected to the end of said first pair of wiper blades, asecond pair of wiper blades engageable with said resistor and insulatedfrom the first pair of wiper blades and rotatably connected to a hollowshaft which is concentric about said first shaft, an output wiper blademounted to a third shaft which is concentric with the first and secondshafts and insulated therefrom, driving means mechanically connected tosaid third shaft and comprising a bearing-to-station computer, and aninput from said phase reversing circuit connected across the first andsecond shafts.

8. A synthetic A/N range for a pilot training device comprising, anoscillator, first, second, and third electronic valves receiving anoutput on their grids from said oscillator, a transformer with one endof its primary connected to the plate of the first electronic valve, theopposite end of the primary connected to the plate of the thirdelectronic valve and the mid-point of said primary connected to theplate of the second electronic valve, a cam supported for rotary motion,a biasing voltage controlled by said cam and triggering said first andthird electronic valves so that when one is conducting the other iscutoff, a range leg selector comprising an annular resistor, a firstpair of slide contacts connected electrically together and engageablewith said resistor and receiving one side of the output voltage of saidphase reversing circuit, a second pair of slide contacts connectedelectrically together and engageable with said resistor and receivingthe other side of the output of said phase reversing circuit, fourgrounded contacts engageable with said resistor at the mid-pointsbetween the first and second pairs of slide contacts, an output contactslidably connected to said resistor, a bearing-to-station computermechanically connected to said output contact, and the output of saidoutput contact dded to an output of said oscillator to produce a signalindicative of the orientation of said pilot training duvice relative tothe synthetic radio range.

9. A synthetic A/N range for a pilot training device comprising, anoscillator, a phase reversing circuit receiving an output of saidoscillator and reversing it periodically in response to a cam supportedfor rotary motion and formed with a pair of projections which coverone-half of the periphery of said cam and with one of said projectionsbeing substantially larger than the other, a range leg selectorcomprising an annular resistor, first, second, third, and fourthgrounded contacts engageable with said resistor and set to the annularpositions of the on-course legs of said range station, a first pair offeed-in contacts receiving one side of the output of said phasereversing circuit and feeding it to said resistor at the mid-pointsbetween the first and second, and third and fourth grounded contacts,respectively, a second pair of feed-in contacts receiving the other sideof the output of said phase reversing circuit and feeding it to themid-points EARL T. HEALD.

10 REFERENCES CITED The following references are of record in the fileof this patent:

UNITED STATES PATENTS Number Name Date Blenman Oct. 3, 1944 Muller Mar.23, 1948 Lang Feb. 1, 1949 White Mar. 8, 1949 Muller July 19, 1949Susdorf Jan. 2, 1951

